IMAC Delro 2.5M Raven Build

[MattyMatt]

I just read through your thread, and i will caution you about the pocket hinging. Most companies got away from this because of the issues with the aileron effectiveness due to the gap that the pocket hinge creates when it moves. If you are just putting this together to go fly then fine... but if you want it to snap, do not pocket hinge the ailerons.

 

[Wacobipe]

MattyMatt, just to make sure I understand what your saying...

I think you are saying I should leave the hinges V- shaped and use something like Robart hinge points, then seal the gap the traditional way. You would do this as opposed to mimicking the type of hinging used in full scale aerobatic ships where the hinges are hidden, then surfaces of the wing extend rearward, and the round LE of the aileron is inserted into that ( see image) is that a correct understanding of what you were saying or am I confused?

Thanks for the input!

 

[MattyMatt]

MattyMatt, just to make sure I understand what your saying...

I think you are saying I should leave the hinges V- shaped and use something like Robart hinge points, then seal the gap the traditional way. You would do this as opposed to mimicking the type of hinging used in full scale aerobatic ships where the hinges are hidden, then surfaces of the wing extend rearward, and the round LE of the aileron is inserted into that ( see image) is that a correct understanding of what you were saying or am I confused?

Thanks for the input!

View attachment 7459

That is correct.

 

[Wacobipe]

That is correct.

So can someone explain to me why this design concept is used/works on full scale but not on our models? I'm quite curious to hear everyone's opinions.

 

[Wacobipe]

Hey Wacobipe!

I'm glad to see you putting one of these together. I have one that was built by Delro themselves and will be flying it in IMAC for the 2015 season. I'm flying the 3.1M version.

I'm also located not too far from you, in Greensboro NC. Also, Volgelsang Aeroscale is the dealer/importer for all Delro products in North America now, and they are located in Chapelhil NC!

I haven't been on the web much the last two-three months due to work and time, but feel free to reach out with any questions you may have.

This plane flys extremely well even on a 150/cans. Actually, I'm using a DA150 and canister setup in the one I have and fly Unlimited.

MattyMatt, what is the flying weight of your Raven?

Delro flew their prototype of the 2.5m Raven on an 80 cc engine. DA says you should use a 100-120cc which seems ridiculous for this plane ( not flying 3D, I fly IMAC style). The target weight according to Delro is 22 pounds. My 26% Pitts M12 has a 76" wingspan, weighs 25 pounds, and flies perfectly on a DA60 so I can't see how this Raven (with much less drag than a biplane) needs more than a DA70 to fly beautifully. On the other hand a DA100 used isn't much more expensive, has more available aftermarket parts, and would be a very safe choice.

What are your thoughts?

 

[MattyMatt]

So can someone explain to me why this design concept is used/works on full scale but not on our models? I'm quite curious to hear everyone's opinions.

There are a lot of things they do that doesn't work well in RC and there are a lot of things we do that don't scale up well. It's physics.

You probably aren't aware, but many prototypes have been made with the pocket hinges, and we're not put into production because they didn't work well. It is very critical about the gap made between the front of the aileron and the back of the wing. The pivot point of the aileron...

On one particular plane we had 45 degrees of aileron throw with the pocket hinging for the plane to snap at the same speed as the second prototype with 25 degrees and the only difference was the conventional robart style hinging.

On the other side, look at horizontal stab position of almost all full scale aerobatic planes; they are at the top of the fuse. On our models, if you do this the coupling is horrible.

 

[MattyMatt]

MattyMatt, what is the flying weight of your Raven?

Delro flew their prototype of the 2.5m Raven on an 80 cc engine. DA says you should use a 100-120cc which seems ridiculous for this plane ( not flying 3D, I fly IMAC style). The target weight according to Delro is 22 pounds. My 26% Pitts M12 has a 76" wingspan, weighs 25 pounds, and flies perfectly on a DA60 so I can't see how this Raven (with much less drag than a biplane) needs more than a DA70 to fly beautifully. On the other hand a DA100 used isn't much more expensive, has more available aftermarket parts, and would be a very safe choice.

What are your thoughts?

I'd go for the 100l. For a few reasons.

1. More power
2. Nose weight, you'll probably need the nose weight. I think the 100L is about 5 lbs, the 70 is only 3.5 lbs.
3. More airplanes available in the 35% class than the 70

 

[Wacobipe]

Thanks for that feedback MattyMatt...I will take all that info in consideration.

 

[Jetpainter]

I have to go with Matt here. The 100L sounds like the way to go for all the listed reasons. I'm also wondering about your 22 pound goal. I don't know what kind of weight other people have built the 2.5 Raven at, but my Carf 2.3 meter Extra 330L weighs 21.75 pounds with a GP61 and a can, and it's quite a bit smaller. I know the small Carf's like mine tend to be heavy, but 22 pounds seems pretty optimistic for a composite airplane the size of your Raven. All that being said, if you could build it at 22 pounds it should fly great!

 

[Wacobipe]

Worked on the wheel pants today...I've found working with a composite fuse is a bit like working with a greased pig...nothing to grab onto without worrying about breaking something...so I figure if I can get it up on it's gear that will help. Epoxied the inner and outer axle supports into the wheel pants. I plan to glass over these mounts for a bit more strength once the Hysol dries on this...the more I work with this mount system the more impressed I am with the idea!